KGF (Keratinocyte Growth factor) has been found to induce proliferation and differentiation of alveolar type II cells in vitro. In addition, KGF prevents lung injury when given prophylatically in several models of lung injury including bleomycin, radiation, and hydrogen peroxide. However, the mechanisms whereby KGF mediates these effects are unknown. Our hypothesis is that KGF mediates, at least in part these actions by inducing type II cell differentiation using distal effectors of the PI3Kinase signaling cascade. We will study signal transduction pathways of rat alveolar type II cells in primary cultures. Understanding these signaling mechanisms would provide potential targets for the treatment of lung injury.